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The term “climate change” generally refers to
changes in our climate that have been identified since the beginning of the
mid nineteenth century.
Our planet’s climate is always changing. In the
past it has altered due to natural causes but at present the changes have
accelerated as a result of human behaviour rather
than natural forces. Indeed, the natural “greenhouse effect” – by which the Earth’s
atmosphere traps energy from the sun warming our planet to support life – is
being heavily disturbed.
The greenhouse effect is the phenomenon by which
the Earth’s atmosphere acts like the glass roof of a greenhouse, allowing the
heat of the sun to enter, and then preventing it from escaping, in effect
capturing it. Greenhouse gases, or “GHGs”, such as
carbon dioxide and methane present in the atmosphere have the ability to trap
the infrared rays reflected by the Earth. The greater the quantity of GHGs, the more the atmosphere will heat up.
 This
phenomenon is essential for life on Earth to exist, keeping Earth’s average
temperature around 14 degrees Celsius.
(Source:http://www.global-greenhouse-warming.com/effect-green-house.html )
In 2007 the Intergovernmental Panel on Climate
Change (IPCC) and Al Gore Jr. were awarded the Nobel Peace Prize for “their
efforts to build up and disseminate greater knowledge about man-made climate
change and to lay the foundations for the measures that are needed to
counteract such change".
The IPCC Fourth Assessment
Report launched in 2007, is the result of 3 years of collaborative work by three Working Groups
consisting of 3 600 scientific experts and reviewers. Over 4 500
scientific articles were consulted and 300 comments from governments were
taken into account.
The AR4 report confirmed that global climate change is
happening because the Earth’s atmosphere is being loaded with man-made
greenhouse gases. Carbon dioxide is emitted by burning fossil fuels for power
and by deforestation, while methane is released from paddy fields, animal
husbandry and landfills.
The IPCC unequivocally
states that: “Most of the observed
increase in globally-averaged temperatures since the mid-19th
century is very likely due to the observed increase in anthropogenic
greenhouse gas concentrations”.
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The carbon dioxide level in the atmosphere reached 385 ppm in 2006,
unprecedented in the past 650 000 years of climate record.
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Eleven
of the last twelve years (1995-2006) rank among the warmest years in the
instrumental record of global surface temperature.Because of the amount of accumulated
greenhouse gases in the atmosphere, over the next two to three decades
global warming will increase almost independent of global greenhouse gas
emissions scenario.
The IPCC projects
that in 2100, the global temperature will have increased by 1.8-4.0 degrees
Celsius.
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 The
warming of sea water leads to sea level rise. Sea levels have risen faster in
the last decade than in the previous 30 years. The total rise in sea level
during the twentieth century is estimated to be 0.17 m.
Global mean sea
level is projected to rise by 9.88 cm by the year 2100, but much larger
increases cannot be ruled out.
For Bangladesh, for example, the current sea level rise
projections would mean that in 150 years from now, sea level would have risen
b 1.5 m and 22% of the land would be submerged, affecting 17 million people.
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